Actually there are many birds that would suit your area. YOu are not as cold as I am and not as blazing hot as Florida. Generally speaking many of the dual purpose birds can adapt to your climate.
I know one fellow that lives in CA and he definitely see a difference in performance based on breed, so sometimes test driving a particular strain is be htes you can do.
Some breeds are better foragers than others. SOme hang around the feeds all day, others go off to forage And stop by the feed bunks occassionally. In my opion this can vary by how they were raised. WHen I have a broody hen that covers the area well, her chicks do too.
YOu will need to spend the time to read up on the different birds. It does take a long time to gather the information. Try the farming with heritage breeds thread started by Yellow House Farm.
You will need to decide how much meat you want from your birds. MOst of the heritage birds, those that I have tried , are not very meaty. Finding a good meat bird has led me to well bred buckeyes and bresse. THe buckeyes are from AL so they should do well in your area I would suppose. THe bresse have very good muscling on the few that I have, so they might work out as meat birds.
Egg layers. THe best egg layers need a great deel of nutritional support. THe best layers were designed to have high quality feed in front of them 24/7 and need to only move their head to get water. Of course the commercial meat chickens are in the same boat. A foraging bird uses a great amt of energy to get around and has less to put into eggs or meat production. But the bonus maybe that the meat and the eggs are of better quality even if the egg numbers are fewer and the meant production is at a slower rate.
Improving the land is a lot of work. Encouraging the insect life as a source of protein seems to be the way to go; a variety of vegetation for shelter, food, etc is a challenge. Small fruit bushes and trees. Grasses of different types.
Check out Yellow House Farm's info -- Joseph breeds dorkings for meat and free ranges them.